Metronidazole by Any Other Name Could Be Deadly

Posted on
7/01/11

MT, a 47-year-old female, presents to her primary care physician with a persistent cough, shortness of breath, chest pain, chills, sweating, and a 102°F fever. Her PCP notes crackling noises in her lungs which, along with her other symptoms, suggest pneumonia. Chest x-rays confirm this diagnosis. The PCP writes a prescription for metronidazole 500 mg every 6 hours and advises MT to get plenty of rest. The next day, after arriving home from work, MT's husband finds her lying in bed unresponsive and barely breathing. Paramedics arrive and while attending to MT note a bottle of metformin next to her bed. Upon questioning, MT's husband denies she is diabetic. A blood glucose test determines a concentration of 35 mg/dL. MT is given 25 mg of 50% dextrose and rushed to the emergency department. It is later determined that the pharmacy accidentally gave MT metformin in place of metronidazole. As a result she experienced severe hypoglycemia due to the medication error.

Background

A medication error is defined as a preventable error due to inappropriate prescribing or administration of a drug.1 Injuries incurred from medication errors are called adverse drug events (ADEs). According to the Centers for Disease Control and Prevention (CDC), ADEs are associated with more than 700,000 emergency room visits and 120,000 hospitalizations each year.2 In an effort to reduce the occurrence of medication errors, leading patient safety organizations, including the Institute of Safe Medication Practices (ISMP) and The Joint Commission, have developed tools and methodologies for health care professionals.

ADEs can be caused by a variety of factors, including look-alike/sound-alike (LASA) medications, illegible physician handwriting, transcription mistakes, computer entry errors, and patient misunderstandings regarding drug administration instructions. In the case study presented above, the error resulted from confusion due to the LASA drug pair of metronidazole/metformin. Involved in a large proportion of ADEs, LASA drug pairs were associated with more than 26,000 errors reported to the US Pharmacopeia (USP) from 2003 to 2006.4 As the baby boomer population advances in age and more drugs are approved by the FDA each year, the rates of LASA-related medication errors are expected to increase. Therefore, it is extremely important that health care professionals make a concerted effort to reduce the occurrence of these errors.

The first step to avoiding LASA-related errors involves recognizing and identifying LASA-prone drug pairs. Both the ISMP and the FDA have developed lists of confused drug names that are commonly involved in medication errors.5 Similarly, the Joint Commission requires accredited organizations to develop lists of LASA drugs, which should be reviewed and revised annually.6 In addition, the USP developed The Drug Error Finder, a free searchable database that provides information about medications, including LASA drugs and the severity of errors associated with them.7

Reducing the risk of LASA-related medication errors requires proactive methods. These include using advanced technologies such as E-prescribing or electronic medical records (EMRs) for order entry, separating products with similar names to different shelves or areas in the pharmacy, identifying which LASA drugs commonly cause medication errors in an organization, and creating awareness of LASA-related errors among colleagues. Taking other key proactive methods, prescribers should (1) educate patients about their medications, which includes explaining the purpose of each drug they take; (2) write the indication for each drug on the prescription; and (3) implement read-backs on verbal orders.4

As part of a more global solution to LASA-related medication errors, several medical safety organizations--including the ISMP, FDA, and the Joint Commission--have promoted the use of TALL-man lettering of medication labels and prescriptions. TALL-man lettering uses both lower- and upper-case letters to draw attention to the dissimilarities in drug names.8 For example, the error described in the case study above may have been avoided if the medications were labeled metroNIDAZOLE and metFORMIN, as suggested by the ISMP. Indeed, studies have shown that using TALL-man lettering can help make LASA drugs less prone to mix-ups.9

While medication errors remain the focus of patient safety programs in the US and around the world, further efforts to promote awareness of the issue and to develop advanced preventive methods are necessary to reduce the prevalence and burden of ADEs. The ISMP, FDA, and Joint Commission have developed materials and tools to help health care professionals identify and prevent medication errors before they occur. As the last line of defense against medication errors, pharmacists should take an active role in ensuring that LASA-related errors are identified and corrected before they can harm patients. As such, pharmacists should remain up-to-date with regard to drugs added to current lists of LASA medications and contact the prescribing practitioner when a prescription raises LASA concerns.

4. Hicks RW, et al. MEDMARX data report. A report on the relationship of drug names and medication errors in response to the Institute of Medicine's call to action. Rockville, MD: Center for the Advancement of Patient Safety, US Pharmacopoeia; 2008.